Numerical and laboratory generation of internal waves from turbulence

Numerical simulations of internal waves that are generated from eddies within a mixed region are described and are directly compared to laboratory observations. The mixed region is created in the laboratory by an oscillating grid at the top of a uniformly salt-stratified region. A tank with a length-to-width ratio of 5:1 is used in order to visualize the internal waves and, as such, large-scale waves are produced from a mean circulation which develops in the mixed region. In addition, smaller-scale waves are generated from the turbulent eddies. Fully non-linear numerical simulations in two dimensions of a mixed region overlying a uniformly stratified region are performed to investigate separately the large-scale and small-scale generation of waves from a mixed region, and the qualitative results compare well with the experimental results. This suggests that the first order dynamics of the laboratory experiments may be captured by the simulations of the two-dimensional model.